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A063613
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Smallest k such that 7^k has exactly n 7's in its decimal representation.
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0
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2, 1, 14, 11, 26, 29, 49, 33, 67, 81, 84, 96, 101, 95, 89, 132, 163, 160, 137, 152, 185, 177, 195, 230, 205, 188, 214, 267, 274, 288, 325, 307, 286, 285, 270, 311, 324, 353, 318, 336, 309, 329, 403, 375, 432, 436, 447, 479, 401, 459, 491
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OFFSET
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0,1
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LINKS
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MATHEMATICA
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a = {}; Do[k = 1; While[ Count[ IntegerDigits[7^k], 7] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
Module[{p7=DigitCount[#, 10, 7]&/@(7^Range[500])}, Table[Position[p7, n, {1}, 1], {n, 0, 50}]]//Flatten (* Harvey P. Dale, Apr 08 2017 *)
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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